Abstract: The system consists of a series of programs that enable a user to investigate possible toughening mechanisms against crack growth in composites and brittle materials consisting of different combinations of materials and containing planar interfaces and elliptically shaped microstructures. The programs begin with various materials, sizes and orientations of microstructures, distances of a crack from a material interface, and possible formulas for energy absorption mechanisms of interest to the user. They then allow a crack to advance toward an interface numerically integrate over a circular and microstructural regions and thus calculate the balance of various energy quantities during crack advance. They then transform the final calculations into a graph display of net energy per incremental length of crack advance versus crack distance from the microstructural entity in question.